<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
	</head>
	<body>
		输入字母：<input type="text" />
	</body>
	<script type="text/javascript">
		let input=document.querySelector("input");
		input.onkeypress=function(){
			let code= event.keyCode;
			console.log(`你输入的内容是${event.key},ASCLLcode:${code}`);
			if(code<65||code>122||(code>90&&code<97)){
				event.preventDefault();
				alert("不能输入非字母");
			}
			if()
			
		}
	</script>
</html>
